Drivers are being warned to take care as temperatures stay below freezing Wales is braced for Arctic conditions as bracing Scandinavian winds see the mercury plummet further.
Overnight snowfall fell in parts of Powys and Monmouthshire with around 7cm (3in) on higher ground. It has also fallen in the Gwent valleys and is spreading further west.
A warning of heavy snow in Powys has been issued and some schools have shut.
Temperatures are expected to reach freezing with added windchill making it feel more like -5 or -10C (23 – 14F).
More than 30 schools across Wales have closed or partly closed due to the bad weather with more school closures expected as the morning goes on.
Strong winds and snow showers are forecast for Tuesday, due to to a blocking weather pattern bringing very cold north-easterly winds.
Bad driving conditions have been reported on the A465 Head of the Valleys road between Tredegar and Abergavenny due to snow.
There are reports of 5cm (2in) of snow on the carriageway and only one lane is open.
The Met Office has issued a warning of heavy snow in Powys.
It says snow showers spreading from the east on Tuesday morning are expected to see accumulations of 2 to 4cm (0.7 – 1.5in) in places, with up to 8cm (3in) over higher ground.
It is also warning that icy stretches will also form on untreated surfaces.
The public are advised to take extra care and refer to Traffic Wales for further advice on road conditions.
BBC Wales meteorologist Derek Brockway said the snow was likely to drift because of the strong winds.
He said the brisk temperatures, snow showers and strong winds will last into Wednesday.
“The wind is going to be getting up on Tuesday and Wednesday. It will become fresh to strong and it’s going to make it feel bitterly cold,” he said.
“It will feel -5C to -10C typically.
“There will be an increased risk of frozen pipes because of the wind pushing more cold air.
“There’s also some snow in the forecast, generally after midnight on Monday, and snow showers that are widespread across Wales.
“There might be a couple of inches on high ground and it could be blowing around, drifting.”
Gavin Hill-Smith from the AA said the organisation had drafted in extra recovery teams in Wales and was keeping surplus staff on stand-by.
He said: “Wales has been one of our busiest areas over the past few days.
“A lot of cars are breaking down in these conditions because of flat batteries, frozen engines and frozen cooling systems.
“When the radiator is frozen the engine will overheat. This something you normally see at -35 C but because people do not keep their anti-freeze levels at 50:50 and top up with water, the solution will freeze at a few degrees below freezing.
“We also have reports from some parts of north and mid Wales that cars are seeing their diesel wax over. This is something you would normally associate with ice truckers travelling through Siberia and illustrates how bitterly cold it is for the end of November.”
The rest of the week is expected to remain very cold with some snow showers.
The winds should ease on Friday but temperatures will remain on the cold side with a risk of some rain and snow.
BBC Wales has the latest online and weather updates.
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